Heat exchanger

ABSTRACT

A heat exchanger for heating liquids, and more particularly a heat exchanger for heating swimming pools and for heating water used for household purposes, industrial purposes and the like. A plurality of gas fired generators radiates toward one or more clusters of water conducting tubes forming an efficient absorbing media of infrared energy. The infrared radiation used is in the range of about 1.0 to 6.0 microns in wavelength. The efficient coupling of infrared generators to a heat exchanger mechanism to utilize all available BTU generation is achieved without passage of the energy beyond the tubes and thereby avoiding damage to opposed generators and without substantial carbon monoxide being generated as a product of combustion.

United States Patent [191 Murtland, Jr.

[ Apr. 30, 1974 HEAT EXCHANGER 2,379,820 7/1945 Mendez 219/365 X [76] Inventor: James B. Murtland, Jr., R.D. NO. 1, 31 ,382: 21:32? 3:11? Box 475A, Natrona g Pa- FOREIGN PATENTS OR APPLICATIONS 15065 7 789,345 l/l958 Great Britain 126/92 B [221 1971 414,080 6/1946 Italy 21 APPL 186 993 553,466 2/1958 Canada 219/299 Primary ExaminerA. Bartis [52] us. c1 122/356, 1262/1332 (1;, 241391//239296, Ammey, Agem, or Fi B -0wn, Murray, Flick &

P kh 511 Int. Cl. F22b 21/10, F24h 1/12 8c am [58] Field of Search 219/296-299,

219/301-309, 311, 354, 365; 126/350 R, 91 [57] ABSTRACT R, 91 A, 92 R, 92 B; 431/326-328; 122/356, A heat exchanger for heating liquids, and more partic- 335 333 355 ularly a heat exchanger for heating swimming pools and for heating water used for household purposes, 56 References Ci industn'al purposes and the like. A plurality of gas 1 ed UNITED STATES PATENTS fired generators rad1ates toward one or more clusters 4 7 2 N I 122 355 x of water conducting tubes forming an efficient absorb g z a /35 6 ing media of infrared energy. Theinfrared radiation I a n used is in the range of about 1.0 to 6.0 microns in 2,598,840 6/1952 Schutte 122/355 X 3,267,910 8 1966 Guerrieri 122/356 Wavelength The efficlent phng of Infrared genera- 1966339 7/1934 219/301 X tors to a heat exchanger mechamsm to utilize all avail- 3,304,933 2/1967 Bates 219/392 X able BTU generation -is achieved without passage of 3,167,066 1/1965 Hughes 219/301 UX the energy beyond the tubes and thereby avoiding ,2 1.903 8/l940 hy--- L 122/356 damage to opposed generators and without substantial carbon monoxide being generated as a product of vans 1 b 1,870,640 8/1932 Nash 6161... 126/91 A ux com 1,725,832 8/1929 Shriner 219/297 8 Claims, 5 Drawing Figures "'6 -1 36 l I 11 22c Pl 9 v 0 I n; I 1

I o o 22a i ,I l8 3 I o o 32 a0 O O M --220 11 t i 5;;- 1 17 as O O )i 2a o O y l i, O O O il I 24 '1 12 /4 PATENTEDAPR so 1924 SHEET 2 OF 2 FIG. 4.

HEAT EXCHANGER BACKGROUND OF THE INVENTION sult in temperaturesv of 3,000 to 5,000F at the flame point. However, considerable carbon monoxide and other undesirable products of incomplete combustion can result because-of the drastic temperature gradients through the combustion zone. Aside from the generation of undesirable gases, however, the major disadvantage of conventional heating techniques is that they are wasteful and costly. That is, the products of combustion comprising heated gases, are caused to pass upwardly through a coil or system of thin tubes where the heat is transferred to water flowing through the tubes mainly by convection. This is inefficient with a large amount of the heat passing to the atmosphere and normally requires that the heat exchanger be of the horizontal or complete containment type. That is, the water must flow through a horizontal conduit section in order that it will remain within the heating zone for a sufficient time in order to absorb enough heat to raise its temperature.

Another disadvantage of conventional liquid heaters of this type is that the tubes which carry the water during heating, normally formed from copper or some other material of high heat conductivity, tend to form an oxide on the surfaces thereof which acts as an insulator, cutting down the efficiency of the heat transfer process.

These drawbacks of conventional heaters are particularly acute in swimming pools heaters where large amounts of heat are required to raise the temperature of the pool even a few degrees.

SUMMARY OF THE INVENTION In accordance with the present invention, heat transfer apparatus is provided for heating liquids comprising conduit means through which the liquid to be heated flows, and means adjacent the conduit means for generating infrared wave energy and for directing it against the conduit means whereby infrared wave energy absorbed by the conduit means will be transferred to the liquid flowing therethrough by convection.

With an arrangement of this sort, the absorption of infrared wave energy is extremely rapid. If bubbles or air pockets should occur within the tubes or conduits carrying the liquid, it is possible that the material from which the conduits are formed may melt. Accordingly, in order to prevent this condition, the conduits which carry the liquid to be heated are preferably arranged vertically or other provision made in order to prevent the formation of any stagnant air bubbles. Additionally, the flow of liquid through the conduits must be rapid enough in order to prevent the formation of steam.

The conduits should be formed from a material of high conductivity and have. a surface of high emissivity in order to provide maximum absorption of the infrared wave energy. For this purpose, copper tubes have been found to be most desirable since, in use, a dark oxide forms on the outer surface of the tubes forming an essentially black surface which has maximum absorptive capabilities for the infrared wave energy. Furthermore the arrangement of conduits should be such as to permit maximum exposure to the generated infrared rays which travel in straight lines similar to rays of visible light.

In one embodiment of the invention shown herein, four infrared generators are disposed around a plurality of conduits carrying liquid to be heated such that the infrared energy from the heaters strikes multiple sides of the conduits. In an arrangement of this-sort, care must be taken to assure that each' conduit is in the line of sight of a generator in order that infrared en ergy will be absorbed by it. Infrared energy must be.

prevented from traveling from one generator and across to another generator since this will create excessive heat which will damage or possibly destroy the generators.

Instead of using only four generators around a cluster of vertical conduits, the number of generators may be 7 increased to provide a hexagonal or even octagonal configuration, for example. Again, care must be taken to dispose the conduits within the space defined by the surrounding generators such that infrared energy cannot pass through the cluster of conduits to agenerator on the other side of the configuration.

In another embodiment of the invention, the conduits which carry the liquid to be heated are disposed in a single vertical plane with infrared generators positioned on one side of the conduits and a reflective surface on the other side such that any infrared energy which passes between the conduits will be reflected backwardly and be absorbed by the conduits and, hence, the liquid flowing therethrough. Another possibility is infrared generators on opposite sides of a row of conduits, in which case the conduits will normally be staggered.

The above and other objects and features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification, and in which:

FIG. 1 is an elevational view, partly in section, showing one embodiment of the invention wherein four infrared heaters are spaced around a cluster of vertical conduits through which water or liquid to be heated passes;

FIG. 2 is a cross-sectional view taken substantially along line II-II of FIG. 1;

FIG. 3 is a cross-sectional view, similar to that of FIG. 2, of an alternative embodiment wherein six infrared heaters are spaced around a cluster of vertical tubes in a hexagonal configuration; I

FIG. 4 is a crosssectional view of still another embodiment of the invention wherein infrared heaters are disposed on one side of a row of vertical conduits, a reflective surface being on the other side; and

FIG. 5 is a cross-sectional view of still another embodiment of the invention wherein infrared heaters are disposed on opposite sides of two rows of staggered vertical conduits.

With reference now to the drawings, and particularly to FIG. 1, the arrangement shown includes a lower header or manifold 10 adapted for connection through conduit 12 to a source of liquid, such as water, to be heated. The water, for example, may be forced into the manifold by means of a suitable pump, generally indicated at 14. At the upper end of the apparatus is an exhaust header or manifold 16; and between the manifolds 10 and 16 is a plurality of conduits 18, perhaps best shown in FIG. 2. Heated water is withdrawn from the upper manifold 16 through fitting 20.

Surrounding the vertical conduits 18 between the manifold 10 and 16 are four infrared heating devices 22A, 22B, 22C and 22D. The infrared heating device may, for example, be Type C-1095 I-IDS manufactured and sold by Van Dorn Company of Cleveland, Ohio. Infrared generators of this type utilize a metallic network that is designed to convert the latent heat energy of a combustible fuel gas mixture to infrared energy emissions. With specific reference to generator 22B shown in cross section in FIG. 1, it includes a fuel nozzle 24 through which natural or other combustible gas is injected. The gas passing through the nozzle 24 mixes the air in a plenum chamber 26, the mixed gases passing through a Venturi tube 28 and then over a baffle 30 into a plenum chamber 32. Covering the open side of the housing 34 which encloses the nozzle 24, the Venturi tube 28, baffle 30 and plenum chamber 32 is a series of wire-mesh screens 36.

Briefly, the operation of the infrared generator is as follows: The mixture of air and gas, after passing through the Venturi tube 28, expands into the plenum chamber 32 and then evenly diffuses through the mesh grip 36. As the mixture filters through the grid, it is ignited and complete combustion is obtained, usually within the confines of the grid. A complete catalytic oxidation of the air-gas mixture is achieved within the surface confines of the grid structure without flame. In this process, the grid structure emits infrared wave energy having a wavelength in the range of about 1.0 to 6.0 microns. This infrared energy then travels away from the grid or mesh 36 along a straight-line path of travel in the same manner as visible light energy.

As the infrared wave energy thus generated strikes the tubes 18, it is absorbed. The absorbed heat is transferred through the walls of the conduits 18 by conduction to the liquid flowing therethrough. The heat transfer process is extremely efficient and serves to rapidly raise the temperature of the liquid flowing through the conduits 18. Care must be taken, however, to insure that the pump 14, for example, pumps the liquid through the conduits 18 at a sufficiently rapid rate in order to prevent the generation of steam within the conduits or the manifold 16.

The products of combustion produced by the burning gas at the wire-mesh screens 36 passes upwardly and along the direction of arrow 38 through a space between the upper edges of the generators 22A-22D and the lower surface of the manifold 16. If desired, fins 40 may be provided on the lower, outer edge of the manifold 16 in order to absorb at least a portion of the heat passing out of the system with the products of combustion. Note that the conduits 18 in FIG. 2 are staggered such that each conduit is exposed on at least two sides to infrared wave energy. Note also that the conduits 18A and 18B are tangent to conduit 18C in both directions. The same is true of conduits 18D and 18E with respect to conduit 18F. This is necessary in order to maximize the surface area of each conduit exposed to infrared wave energy while, at the same time, preventing passage of infrared energy from one generator to a generator on the opposite side of the apparatus. If this were to occur, possible damage to the grid structures 36 or other parts of the infrared generators could occur.

With reference to FIG. 3, another embodiment of the invention is shown wherein six infrared generators 42 are spaced around a cluster of vertical conduits 44 in a hexagonal configuration. As will be understood, this increases the capacity of the heat transfer device by a factor of 50 percent over the arrangement shown in FIG. 2. Further capacity can be added, for example, by providing an octagonal configuration. Again, care must be taken in the size and spacing of the tubes to prevent infrared rays from a generator from passing through the tubes 44 to a generator on the other side.

In FIG. 4, another embodiment of the invention is shown wherein the conduits 46 all are in a common vertical plane connected between a lower header or manifold 48 and an upper header, not shown. In this case, there are three infrared generators 50 disposed on one side of the row of conduits 46. Any infrared energy which passes through the spaces between conduits 46 is reflected from a reflective surface 52 on the side of the conduits opposite the generators whereby it is returned back to the conduits and absorbed.

In FIG. 5, still another embodiment of the invention is shown which is similar to that of FIG. 4 except that rows 54 and 56 of infrared generators are on opposite sides of two staggered rows 58 and 60 of vertical conduits extending between a lower header 62 and an upper header, not shown. Again, care must be taken to insure that in an arrangement of this sort, the infrared wave energy from a generator on one side of the rows 58, 60 will not pass through to a generator on the other side.

Although the invention has been shown in connection with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

I claim as my invention:

1. Heat transfer apparatus for heating liquids comprising:

a plurality of infrared generators forming at least one opposed pair of each including means for converting a latent heat energy of a combustible fuel gas mixture into infrared energy emission characterized by a path of travel along spaced-apart and substantially straight lines from each generator,

an inlet manifold,

an outlet manifold,

a plurality of tubes connecting said manifolds in a liquid conducting relation for conducting liquid to be heated in a direction normal to said path of travel by the infrared energy emissions from said generators, and

said tubes being spaced one with respect to the other while supported by said manifolds to form at least one cluster of tubes arranged and constructed to intercept substantially all of the infrared energy emissions from each of said generators whereby the said emissions do not pass beyond said cluster of tubes, said infrared generators being secured to and supported by at least one of said manifolds.

2. The heat transfer apparatus of claim 1 wherein said plurality of tubes comprises a plurality of vertical conduit tubes extending between a lower manifold and an upper manifold.

3. The heat transfer apparatus of claim 2 wherein said vertical conduit tubes are spaced to form a cluster of tubes such that infrared energy from one generator of said opposed pair will not pass through said cluster of tubes to the other generator of said pair.

4. The heat transfer apparatus of claim 3 wherein said plurality of infrared generators comprises four generators spaced around said cluster of vertical tubes in a rectangular configuration.

5. The heat transfer apparatus of claim 3 wherein said plurality of infrared generators comprises generators spaced around a cluster of vertical tubes in a hexagonal configuration.

6. The heat transfer apparatus of claim 2 wherein said cluster of vertical tubes are arranged in parallel rows with the tubes in one row being adjacent tubes of another row, said plurality of infrared generators comprising at least one generator disposed on each side of the parallel rows such that the generators face each other.

7. The heat transfer apparatus of claim 6 wherein a plurality generators is disposed at each of said side of the rows of tubes.

8. The heat transfer apparatus according to claim 1 wherein said plurality of infrared generators is disposed side-by-side and supported by at least one of said manifolds to form a contiguous enclosure surrounding said plurality of tubes. 

1. Heat transfer apparatus for heating liquids comprising: a plurality of infrared generators forming at least one opposed pair of each including means for converting a latent heat energy of a combustible fuel gas mixture into infrared energy emission characterized by a path of travel along spaced-apart and substantially straight lines from each generator, an inlet manifold, an outlet manifold, a plurality of tubes connecting said manifolds in a liquid conducting relation for conducting liquid to be heated in a direction normal to said path of travel by the infrared energy emissions from said generators, and said tubes being spaced one with respect to the other while supported by said manifolds to form at least one cluster of tubes arranged and constructed to intercept substantially all of the infrared energy emissions from each of said generators whereby the said emissions do not pass beyond said cluster of tubes, said infrared generators being secured to and supported by at least one of said manifolds.
 2. The heat transfer apparatus of claim 1 wherein said plurality of tubes comprises a plurality of vertical conduit tubes extending between a lower manifold and an upper manifold.
 3. The heat transfer apparatus of claim 2 wherein said vertical conduit tubes are spaced to form a cluster of tubes such that infrared energy from one generator of said opposed pair will not pass through said cluster of tubes to the other generator of said pair.
 4. The heat transfer apparatus of claim 3 wherein said plurality of infrared generators comprises four generators spaced around said cluster of vertical tubes in a rectangular configuration.
 5. The heat transfer apparatus of claim 3 wherein said plurality of infrared generators comprises generators spaced around a cluster of vertical tubes in a hexagonal configuration.
 6. The heat transfer apparatus oF claim 2 wherein said cluster of vertical tubes are arranged in parallel rows with the tubes in one row being adjacent tubes of another row, said plurality of infrared generators comprising at least one generator disposed on each side of the parallel rows such that the generators face each other.
 7. The heat transfer apparatus of claim 6 wherein a plurality generators is disposed at each of said side of the rows of tubes.
 8. The heat transfer apparatus according to claim 1 wherein said plurality of infrared generators is disposed side-by-side and supported by at least one of said manifolds to form a contiguous enclosure surrounding said plurality of tubes. 